I'm confused about how the following sentences should be analyzed, in terms of which words are prepositions and adverbs, how the phrases break up, etc.:

She was going home.

She was home.

She was at home.

She got home.

My height is six feet.

I am six feet.

I am about six feet.

He is my height.

He is about my height.

I saw a man my height yesterday.

I saw a man about my height yesterday.

For instance, is it possible that my height falls into different categories in #8 and #9?

EDIT: Ok, now I have one answer from Daniel δ and a some requests for more specific questions.

I'm most concerned about home, about, six feet, and my height.

Daniel δ says that home is an adverb in #1, #2, and #4. I'm assuming this is just a special quirk that happens with home?

I'm not convinced that my height is always a noun phrase, or there's something I'm missing. In #8, if my height is just a noun phrase, that would mean that He, the subject, is actually a height, but he's a person, not a height any other form of measurement (Same for six feet in #6). Daniel δ suggests that #10 is short for "I saw a man who was my height yesterday", but something seems special about this construction. If height is just a noun, then why does switching it for some other noun like lawyer fail? We could say "He is a lawyer" but not "I saw a man a lawyer yesterday". But my height does make sense as a noun in #9, since we can call about a preposition that just takes my height as part of a prepositional phrase...

As FumbleFingers noted, #11 can be interpreted in at least two ways. I'm interested in the sense that fits the analogy #8:#9 :: #10:#11.

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1

That's a lot of work to do, analyzing all your sentences for you. Can you make it easier for us? What exactly are you looking for?
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MitchDec 22 '11 at 0:27

In all cases except the last, about unambiguously means approximately. But in the last case, if you were for example the world's talllest man you might go to see a doctor about your height - but the doctor might actually be average height or even abnormally short.
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FumbleFingersDec 22 '11 at 0:31

... about is usually called a preposition because that's just the "bucket category" for little words we all know but can't fit into any of the major categories. It's such a crude naming system it's barely worth bothering with, but in OP's examples I would say it's functioning as an adjective - or modifier, which I prefer, since it's modifying "my height".
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FumbleFingersDec 22 '11 at 0:36

I saw a man [who was] my height yesterday.Saw is a verb, man is a noun, yesterday is an adverb, who was is understood.

I saw a man about my height yesterday. [Explained above]

Home is special in that it can be a place (noun) or an adverb, with no variation of form. Not all nouns operate that way.

My height in #8 is the same as in #9. He is my height is simply short for (and understood to mean) His height is my height. My height is still a noun phrase. You can understand it as an idiomatic construction; this type of construction does not apply to a wide range of situations (e.g. you wouldn't say he is my idea). It seems to work for personal characteristics such as height, weight, color, and size.

About is an adverb in all your examples but the second interpretation of #11. The basic difference between an adverb and a preposition is that an adverb modifies the verb (or an adjective or another adverb), while a preposition always modifies a noun (the object of the preposition). A simple test is to remove the word in question from the sentence. Does the basic structure change? If not, the word was an adverb. For instance, in He fell down, down is an adverb (modifying fell). If you remove it, the sentence becomes He fell, which still makes sense. However, in He fell down the hill, down is a preposition (modifying the hill). If you remove it, the sentence becomes He fell the hill, which does not make sense. As to your example, He is about my height, it appears that about does modify a noun (my height), so it seems like a preposition. However, removing the word reveals that my height was the direct object of the sentence, not the object of the preposition, and that about had actually been modifying is: He is my height.

The two interpretations of #11 boil down to the difference between about as an adverb and about as a preposition; I saw a man about my height (about is a preposition modifying height) and I saw a man [who was] about my height (about is an adverb, modifying was). It's ambiguous because of the possible ellipsis of who was.

Thanks. See my edit of the question.
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JohnJamesSmithDec 22 '11 at 22:55

I think this is about the level where classifying words (or specific usages thereof) as either adverb or preposition starts to become pointless. In the case of seeing a man about your height it's really overanalysing to suggest about is one or the other part of speech depending on whether the speaker (or hearer) imagines it preceded by an elided "who was".
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FumbleFingersDec 23 '11 at 19:37

About was an adverb modifying is in your comment :) Seriously, I think it makes more sense and becomes more clearcut this way; I don't agree that it's pointless. A part of speech is named according to what it modifies: it's that simple. I would say that what you described is not a worse case of overanalyzation than determining which possible meaning (i.e. seeing a man concerning your height vs. seeing a man who was approximately as tall as you) is intended by seeing a man about your height.
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DanielDec 23 '11 at 19:41

Anyway, the OP specifically asked about the structures behind each meaning, which gives me a good excuse!
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DanielDec 23 '11 at 19:47

The distinction between those concerning and approximately the same meanings does indeed turn on meaningful differences in "parts of speech". All I'm saying is that it becomes meaningless with "I saw a man [who was] about my height". In this case the classification categories and methods of assigning words to roles end up with us toggling the category of the word "about" based purely on exactly how explicitly we perceive "[who was]" to be implied by the construction. IMHO by that point it's a useless distinction.
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FumbleFingersDec 23 '11 at 22:37

The Cambridge Grammar of the English Language takes home to be a preposition and a noun, but never an adverb. In all your examples, it would be a preposition. Similarly, about is always a preposition. The other two, six feet and my height are both noun phrases.

Part of your problem, I believe, is a confusion between category and function. This kind of confusion is rampant. Even though six feet is always an NP, it can perform various functions including: subject (e.g., six feet is too much), object (e.g., His height has reached six feet), and modifier (e.g., a six foot point guard, ok foot not feet).

In I saw a man my height, the NP my height functions as a modifier of man.

Finally, according to CGEL, yesterday is a pronoun. In those sentences, it is functioning as an adjunct.

A preposition always modifies a noun, which home does not. Home is modifying got, which is a verb. About also modifies the verb in all the OP's examples, hence it is also an adverb, not a prep. Also, a pronoun is a substitute for a noun, which yesterday isn't. It is an adjunct, though; specifically an adverb. Now I'm curious as to how you make out that home and about are prepositions and yesterday is a pronoun?
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DanielDec 23 '11 at 19:31

Yes, that's the party line, at least sort of. The NP is usually taken to be the object of the preposition, not the head with the preposition as a modifier. Regardless, there's no good reason for that to be true, and it turns out that it isn't. Consider the OED's entry for for sense 19b: take for granted, leave for dead, for certain, etc. Also, consider out from under the bed. Every dictionary lists from as a preposition, but its complement is the PP under the bed, not an NP. Jespersen show this almost 100 years ago, but it's not well known.
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Brett ReynoldsDec 23 '11 at 20:26

The arguments for home as a preposition include ability to function as a complement to be (prototypical adverbs can't). So you can say I'm home, but you can't say I'm quickly. Similarly, the verb head meaning "set out in a particular direction" takes PP complements and not AdvP complements. So I'll head home supports the preposition analysis. Also you can say I'll come right home even though right commonly modified prepositions, but not adverbs. The only thing arguing against home as a preposition is the lack of an object. But I dealt with that in the comment above.
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Brett ReynoldsDec 24 '11 at 13:03

Yesterday as a pronoun is trickier. First of all, as you say, pronouns "substitute for" nouns (NPs actually). The NP here is the particular day that was yesterday. Today, being Saturday for me, yesterday can replace Friday. Also, like pronouns, yesterday is deictic, that is, it requires contextual information. When I use you the meaning depends on who I'm addressing. Similarly, when I use yesterday it depends what day it is today. Granted, however, the personal pronouns decline for case while yesterday doesn't. Still, it has many characteristics of pronouns.
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Brett ReynoldsDec 24 '11 at 13:10

Now I'm curious about how would about NOT be a preposition.
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Brett ReynoldsDec 24 '11 at 13:11